Yes, the money would ultimately come from the public's own funds (or their insurance). However, the police do work on behalf of the people as a whole... it is not unreasonable to expect that the government pays for the screwups. If anything, it would cause the higher ups to take a very strong interest in the proper use of such tactics. If getting it wrong was an immediate million dollar hit to the budget, I guarantee you they'd triple check everything. Despite the best of intentions (hopefully, they're the best of intentions), the chance of causing harm or pain to innocent people has thus far not been enough to cause police agencies to review the use of these tactics.